The present invention relates to transmit/receive apparatus for pulse radar systems and other microwave communications systems, and more particularly to electronic scan antenna arrays and transmit/receive circuit modules employed in such antenna arrays.
In a typical electronic scan antenna array (ESA) for a pulse radar system, numerous transmit/receive (T/R) circuit modules are arranged in a solid plane and connected to frontally located radiator elements which collectively generate a transmitted radar beam. The beam is normally energized, shaped and directed in azimuth and elevation under electronic control of the signals applied to the individual radiators. An ESA may have 2000 or more radiator elements.
Generally, a pulse radar system generates successive transmit pulses which are distributed through a transmit manifold and microwave circuitry to the various antenna radiators. Between transmit pulses, the radar system receives and processes successive return signals from the antenna radiators. The return signals are processed through microwave circuitry in the T/R module, collected through a receive manifold, and then processed in the system for target identification.
A T/R microwave circuit is normally associated with each antenna radiator. A microwave transmit circuit path operates on each transmit pulse received from the transmit manifold in an antenna transmit mode, and thereby controls the amplitude and phase of the radio frequency (RF) signal generated from the associated antenna radiator.
Inversely, in an antenna receive mode, a microwave receive circuit operates on each return RF signal from the associated radiator to control its amplitude and phase and pass it to the receive manifold.
Previously, transmit and receive circuits were embodied in separate modules, i.e., transmit modules and receive modules. In the current state of the pertaining art, the T/R microwave circuitry is usually embodied in a T/R module having a single T/R channel, i.e, an integrated unit in which various circuit elements are embodied to provide specified transmit and receive functioning for the T/R channel in the unit. The widely accepted modular T/R design approach generally results in reduced manufacturing costs and facilitates maintenance of installed ESA systems.
The pulse radar system employs a programmed digital processor to control amplification, attenuation, and phase shifting of transmit and receive signals, thereby determining the amplitude, direction, and shape of the aggregate RF energy beam transmitted by or received by the ESA. Different phase shifts cause different transmit or receive circuit delays in delivery of individual RF radiator signals to control the pattern with which spherical RF energy wavefronts associated with the different radiators are combined to define the direction and shape of a transmitted or received antenna beam. In the above referenced related patent application Ser. No. 09/158,829 (Docket BD-98-012), entitled A Dual Channel Microwave Transmit/Receive Module For an Active Aperture Of A Radar System, there is disclosed a T/R module having twin or multiple T/R channels for operation in an ESA array of a pulsed radar or other microwave communications system. The invention of the (BD-98-012) application provides better waste heat dissipation, higher RF power operation, and other performance improvements along with economies of manufacture.
The twin channels embodied in a twin T/R module of the referenced invention have substantially identical circuit paths, while sharing certain service circuitry, including power supply and distribution circuitry, logic and control circuitry, and RF signal routing circuitry. This application is directed to such circuit sharing and thus supports improvement in T/R module and microwave system performance along with manufacturing economy.